I'm aware that there are unmanned stations -- not only oil platforms but regular leases. I live in oil & natural gas country (Northern Alberta). What you don't see are the thousands and thousands of guys running around keeping it all ticking.
There are some things that you can automate -- but a lot of things in the oil & gas industry cannot be automated. Specifically, the leg work required to get things started & keep them maintained. Automating those sorts of things requires a pretty advanced AI and I don't see that coming around the corner anytime soon.
You can make things simpler for dumber AIs (or dumber workers) by designing field-replaceable-units with that in mind. It is going to cost more/be less efficient, so as long as a human costs $300k/yr or less, no need, but when that isn't the case, you see "forklift upgrades", etc.
There are some things that you can automate -- but a lot of things in the oil & gas industry cannot be automated. Specifically, the leg work required to get things started & keep them maintained. Automating those sorts of things requires a pretty advanced AI and I don't see that coming around the corner anytime soon.